Motor-pump unit



A 8- 1965 J. J. MATELENA 3,

MOTOR-PUMP UNIT Original Filed Oct. 9, 1983 4 Sheets-Sheet 1 FIG. IA.

INVENTOR JOHN J. MATELE NA ATTORNE S g- 2, 1956 J. J. MATELENA 3,263,619

MOTOR-PUMP UNIT Original Filed Oct. 9, 1965 4 Sheets-Sheet 2 FIG. IB.

INVENTOR,

JOHN J. MATE LENA BY ATTORNEYS Aug. 2, 1966 J. J. MATELENA 3,263,619

MOTOR-PUMP UNIT Original Filed Oct. 9, 1965 4 Sheets-Sheet 5 FlINVENTOR.

HN J. MATELENA BY ATTORNEYS Aug. 2, 1966 J. J. MATELENA 3,253,619

MOTOR-PUMP UNIT Original Filed 001.. 9, 1953 4 Sheets-Sheet 4.

Fl G. 5.

ATTOR N EYS United States Patent 3,263,619 MOTOR-PUMP UNIT John J.Matelena, Trenton, N.J., assignor to De Laval Turbine Inc., Trenton,N.J., a corporation of Delaware Continuation of application Ser. No.315,042, Oct. 9, 1963. This application Oct. 4, 19165, Ser. No. 492,3684 Claims. (Cl. 103-120) This application is a continuation of myapplication Serial No. 315,042, filed October 9, 1963.

The present invention relates to multiple screw pumps such as describedin Montelius Patents 1,698,802, 1,821,- 523, and 1,965,557 respectivelydated January 15, 1929, September 1, 1931 and July 3, 1934. As describedin theses patents, such multiple screw pumps conventionally include aplurality of idler screws which are journalled for rotation in astationary housing and a centrally p ositioued power screw which ismechanically driven through a coupling by a motor having an output shaftaxially aligned with the power screw.

In contrast to such conventional pump and motor arrangements, thepresent invention contemplates the incorporation of the entire screwpump assembly within the motor casing so as to provide an integralmotor-pump unit the axial length of which is approximately one-half thatof conventional motor and pump arrangements. Accordingly, there is alsoa substantial reduction in weight.

In addition to substantially reducing the size and weight of themotor-pump unit, the number of elements is also reduced since the needfor a conventional motor shaft, coupling unit and separate pump casingand bearing are entirely eliminated. Furthermore, previous screw pumpand motor arrangements required the power screw to extend through thepump casing so as to be externally driven and this required the use of ahigh pressure shaft seal to prevent the escape of the pumped fluid alongthe externally projecting shaft.

Yet another advantage of the present invention resides in the fact thatthe elimination of a shaft coupling unit also eliminates shaft alignmentproblems and, even more importantly, eliminates the objectionable noisewhich is often produced by such couplings. In this regard, the reductionof noise is an exceptionally importantfeature since screw pumps areoften selected for a particular application due to the fact that thepumping mechanism is naturally quiet in operation as compared, forexample, to reciprocating piston pumps which have large vibrationcharacteristics. Thus, the reduction of coupling noise makes thecombined motor-pump unit even better suited to those applicationsrequiring quiet operation. Of course, the fact that the pump is entirelyencased within a relatively massive motor structure further tends todamp pump vibrations so that even quieter operation is achieved.

Another advantage of the present invention is that there is achievedgreatly improved center of gravity and radius of gyration values becauseof the reduction in weight and length.

It is therefore a general object of the present invention to provide animproved pump-motor unit having the above indicated structural andfunctional advantages.

It is yet another object of the present invention to provide apump-motor unit wherein the delivery rate of 0 "ice the pump may bevaried in accordance with or independently of the operating speed of thedriving motor.

The above objects as well as others relating more particularly to thedetails of construction and operation will become more fully apparentfrom the following descrip tion when taken with the accompanyingdrawings in which:

FIGURE 1A is a sectional View of the left-hand end of the combinedmotorpump unit;

FIGURE 1B is a sectional view of the right-hand end of the combinedmotor-pump unit;

FIGURE 2 is a sectional view of the left-hand end of the motor pump unitshowing the screws in plan view;

FIGURE 3 is a sectional view of the right-hand end of the motor-pumpunit showing the screws in plan view;

FIGURE 4 is an end view of the motor pump unit with a portion of thecasing broken away in section; and

FIGURE .5 is a simplified illustration of the pumpmotor unit incombination with means for varying the delivery rate of the pumpindependently of the operating speed of the motor.

Referring now to the structural details of the invention as illustratedin FIGURES 1-4, the motor pump unit comprises a motor section generallyindicated by numeral 10 which surrounds and supports the pump sectiongenerally indicated by numeral '12. From the subsequent description ofthe invention it will become apparent that the motor section maycomprise a standard motor of conventional design including both AC. andDC. types which may be either constant or variable speed as well asreversible if so desired. However, for purposes of description it willbe assumed that the motor is a conventional squirrel cage inductionmotor since such motors are most often employed to drive pumps due totheir high starting torque characteristics.

Motor section 10 includes an outer cylindrical casing 14 to which a pairof end plates 16 and 18 are secured by a plurality of bolts 20. Casing14 supports the stator 22 having conventional field windings. 24. Therotor is indicated at 26, comprising the usual squirrel-cage condoctorsand associated core structure, and carries a plurality of blades 27which circulate cooling air through the motor in the conventionalmanner. Rotor 26 is rigidly secured to a sleeve 30 as by keys 28 and theopposite ends of the sleeve are journalled in bearings 32 and 34 whichare carried by end plates 16, 18 and provided with bearing seals 33.

Reference is now made to the pump section 12 which includes acylindrical pump housing 36 formed by a plurality of axially alignedsections 38 secured against rotation relative to each other by means ofcylindrical connecting pins 40. Housing 36 is keyed to sleeve 30 so asto rotate therewith by means of a plurality of keys 42 two of which areillustrated in FIGURE 113. Of course, it will be apparent that each ofsections 38 may be individually keyed to sleeve 30 if so desired,however, this is not generally necessary due to the interconnectionprovided by pins 40.

The pump housing 36 is provided with a pair of lobed bores 44 in which apair of idler screws 46 are received so as to rotate about theirrespective axes as in conventional screw pumps. One end of each idlerscrew is preferably provided with a portion forming a balancing piston48 which is receivable within a cylinder element 33 50 to which highpressure fluid is supplied from the pump outlet chamber 51 through anaxial passage 52 in housing 36, radial passages 54, annular groove 56,radial passages 58 and axial passages 60 the latter of which areprovided in a housing member 62.

The pump housing 36 also contains a central bore 64 which intersectsbores 44 throughout its length and which receives a power screw 66having helical threads in meshing engagement with the helical threads onthe idler screws.

As most clearly shown in FIGURES 1A and 2, the left end of power screw66 extends through a bearing sleeve 68 forming a portion of housingmember 62 so that this member and the pump housing 36 are free to rotateabout the power screw. Externally of sleeve 68, the end of the powerscrew abuts, in view of the pressure difference across the screw, aspider support 70 formed as an integral portion of a casing member 72the latter of which is stationarily secured to the motor casing 16 by aplurality of bolts 74.

Casing member 72 forms the pump inlet passage 76 and is provided withmeans such as threaded bores 78 whereby the inlet pipe connections maybe made to the motor-pump unit. In addition, casing member 72 supports aseal assembly 80 which engages the external surface of sleeve 30 so asto seal the pump inlet from the motor section.

Referring now to FIGURES 1B and 3, the right end of power screw 66 issplined at 82 so as to be non-rotationally secured to a casing member 84having a plurality of pump outlet passages 86 extending parallel to andcircumferentially about the power shaft. Casing 84 is connected by aplurality of bolts 88 to a second casing 90 which, in turn, is connectedto the motor casing 18 by a plurality of bolts 92. Casing 90 supports anoutlet pump seal assembly 94 which surrounds and engages rotary sleeve30 the latter of which is spaced from casing 84 by means of a bearingsleeve 96 so that the sleeve and pump housing 36 are free to rotaterelative to the stationary casing 84. In order to further prevent thepassage of high pressure pump fluid into the motor section, a bleedpassage 98 is provided in sleeve 96 which leads through the pump housing36 back to the pump inlet and thereby provides an escape for the highpressure fluid which passes between casing 84 and sleeve 96.

From the foregoing description of the motor-pump structure it will bereadily apparent that rotation of the motor rotor 26 rotates sleeve 30and the pump housing 36 carrying the idler screws 44 so that the latterexecute a planetary motion about the stationary power screw. As aresult, closed pumping chambers formed by the interengaging screwthreads travel axially along the screws in a manner identical to theoperation of a conventional screw pump wherein the power screw isrotated within a stationary casing carrying the idler screws.

In the foregoing description it was assumed that the pump housing 36 wasdriven at substantially constant speed by induction motor 10. On theother hand, it will be readily apparent that a variable speed motor maybe employed so as to rotate the pump housing at various speeds andthereby provide a variable rate of pump delivery. However, the presentinvention also provides for variable delivery rates even though the pumphousing is driven at constant speed by a constant speed motor. In brief,this may be accomplished by permitting the central power screw to rotatealong with the pump housing but at variable speeds less than theconstant speed at which the pump housing is rotated by the motor.

FIGURE schematically illustrates one arrangement whereby the speed ofthe power screw may be varied from zero up to the speed of the housingin order to vary the delivery rate of the pump. In this system, themotorpump unit 100 is substantially identical to that previouslydescribed and includes a motor casing 101 carrying a stator 102 withinwhich the motor rotor 104 is supported by the pump housing 106journalled for rotation in bearings 108 and 110. Housing 106 carries apair of idler screws 112 and 114 which rotate with the housing as in theprevious embodiment. Housing 106 also includes a central bore whichreceives the power screw 116 one end of which is journalled for rotationin bearings 118. The opposite end of the power screw extends through thepump outlet casing and is connected to an electromagnetic brakegenerally indicated 120.

Brake 120 is entirely conventional and includes a casing 122 supportinga stationary excitation coil 124 surrounding a stator 126 within which arotor 128 is adapted to rotate, rotor 128 being secured to power shaft116. The gap between stator 126 and rotor 128 is filled withfinelydivided ferromagnetic particles suspended in oil which haveinsignificant frictional effect so long as coil 124 is not energized.However, upon the passage of an excitation current through coil 124, amagnetic field is produced across the gap so that the particles cling toeach other forming chains creating a magnetic bond between the statorand rotor. Thus, the power screw 116 may be held completely stationaryor permitted to rotate along with the pump housing at varying speedsdepending upon the amount of current supplied to the excitation coil. Asa result, the volumetric output of the pump may be varied from themaximum which occurs when the power screw is held stationary to asubstantially zero output which occurs when the power screw isunretarded and therefore fully rotates along with the pump housing andidler screws at a substantially equal speed.

Although a magnetic particle type brake has been shown for purposes ofillustration, it will be readily apparent that other types of brakesincluding mechanical friction brakes may be employed to retard tovarying degrees as desired the rotation of the power screw. Furthermore,although it is preferred that the brake be capable of holding the screwcompletely stationary, it will be apparent that a dynamic brake may beemployed to retard rotation of the power screw in varying degreeswithout holding it completely stationary.

Numerous other modifications and alterations will become readilyapparent to those skilled in the art and it is to be understood that theinvention is not to be limited other than as specifically set forth inthe following claims.

What is claimed is:

1. In combination, an electric motor including an annular rotor, a pumphousing mounted within said annular rotor so as to rotate therewith, aplurality of idler screws, means mounting said idler screws within saidhousing for rotation about their respective axes, a power screwpositioned centrally of said idler screws in meshing engagementtherewith so as to form pumping chambers, and means for restrainingrotation of said power screw whereby said pumping chambers advanceaxially along said power sorew upon rotation of said housing andplanetary movement of said idler screws about said power screw.

2. The combination of claim 1 in which said means restraining rotationof said power screw comprises brake means arranged to control the speedof rotation of the power screw relative to the speed of rotation of saidhousing.

3. In combination, a motor having a casing, bearing means supported bysaid casing, a cylindrical pump housing supported by said bearings forrotation about the longitudinal axis thereof, said motor including anannular stator supported by said casing and an annular rotor surroundingsaid housing, means securing said housing to said rotor so as to rotatetherewith about said axis, a power screw having a longitudinal axiscoincident with the axis of said housing, means connected to said motorcasing for supporting said power screw and for restraining its rotation,a plurality of idler screws circumferentially spaced about said powerscrew in meshing engagement 3,263,619 5 6 therewith so as to formpumping chambers, and means References Cited by the Examiner mountingsaid idler screws in said housing for planetary UNITED STATES PATENTSmovement about said power screw upon rotation of said housing by saidrotor so as to axially advance said pump- 4931844 3/1893 schrPder1O3-121 ing chambetrs' 5 1,341,846 6/1920 Golhngs 103-421 4. Thecombination of claim 3 in which said means 68 25 for restrainingrotation of said power screw comprises 2536486 1/1951 B n m 103 120brake means arranged to control the speed of rotation enry of the powerscrew relative to the speed of rotation of said ROBERT WALKER PrimaryExam-net housing. 0

1. IN COMBINATION, AN ELECTRIC MOTOR INCLUDING AN ANNULAR ROTOR, A PUMPHOUSING MOUNTED WITHIN SAID ANNULAR ROTOR SO AS TO ROTATE THEREWITH, APLURALITY OF IDLER SCREWS, MEANS MOUNTING SAID IDLER SCREWS WITHIN SAIDHOUSING FOR ROTATION ABOUT THEIR RESPECTIVE AXES, A POWER SCREWPOSITIONED CENTRALLY OF SAID IDLER SCREWS IN MESHING ENGAGEMENTTHEREWITH SO AS TO FORM PUMPING CHAMBERS, AND MEANS FOR RESTRAININGROTATION OF SAID POWER SCREW WHEREBY SAID PUMPING CHAMBERS ADVANCEAXIALLY ALONG SAID POWER SCREW UPON ROTATION OF SAID HOUSING ANDPLANETARY MOVEMENT OF SAID IDLER SCREWS ABOUT SAID POWER SCREW.